Underreamer



M. MILLER UNDERREAMER P'iled Jan. e. 192s 2 sheets-sheet 1 ...lig M. $5 f kr Al. ll/lT/w. uw

Dec. '27, 1927. 1,654,468

J. M. MILLER UNDERREAMER Filed Jan. 6. 192s yheats-sneek 2,

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vPatented Dec. 27 1927.

arten STATES l 1,654,468 PATENT olf-Fica JAMES M. .MILLER, OF PERRY, OKLAHOMA.

UNDERREAMER.

Application filed January 6, 1926. vSerial No. 79,634.

The object kof this invention is to provide an underreamer for use at the lower end of a well casing, or the like, in well known manner, the device including a -body provided with al vertical bore and with lateral vertically extending slots thru whichv the cutting devices extend, and slots in which mandrel engaging and retaining means are mounted, in the special .manner hereinafter disclosed. Y

A further object is to provide for the formation of the openings in the body in such manner `that the operative elements will serve the purpose for which t-hey are intended, and for which they are specially constructed, in the most effective manner.

With the foregoing and other objects in view, the invention consists in the novel construction and arrangement of elements described, illustrated and claimed, it being understood that modifications may be made within the scope of the claim, without departing from the spirit of the invention.

In the drawings forming part of this application,

Figure 1 shows the device in side elevation.

Figure 2 is a view in vertical section, the section being on line 2-2 of Figure 1.

Figure 3 is a vertical section, in the same plane, the cutting devices being in operative position.

Figure 4 is a vertical section on line 4-4 of Figure 2.

The body may be provided with an upwardly extending threaded portion 11 for connection with the operating element 12, and said body 10 is formed with a vertical or longitudinal bore 13, the lower end being formed as shown at 14 where` a reduced opening 15 is provided, for the purpose indicated below.

The mandrel 16 includes a lreduced portion or shank 17 encircled by a coiled. spring 18, the upper end of which bears against the under side 19 of the element 16. The lower end of spring 18 bears on the upper portion 27 adapted t0 engage the wall 28 at the bottom of each vertical slot 29, and the inner sides of elements 24 are adapted to contact with the tapered portions 30 of the body 10, when the cutters 24 are in closed or inoperative position.

The cutters further linclude the upwardly extending portions or Shanks 32 having slots 33 formed therein, the slots accommodating a transverse pin 33 `which is threaded into the mandrel 16, the pin having slots in the opposite ends thereof in order to provide for correct adjustment, by the insertion of a tool.

Each cutting device 24 is formed with an upper and outer curved portion 3G adapted yto cooperate with the concave portion 37 at the upper wall of eachvertical slot 29, the cooperating portion being especially illus- 'trated in Figure 3. The edge portions at the upper ends of the slots are further curved in a reverse direction with reference to the curved portion 37, in the manner shown at 39.

Retaining devices, for holding the mandrel 16 in the position of Figure 4, and against the expansive action of spring 18, are desigf nated 40 and 41, these devices being pivoted at .42 in slots, such as 43, extending radially with reference to the bore 13, the inner ends of devices or dogs 40 and 41 engaging the mandrel when the cutting devices 24 are inoperative.

Locking devices for the dogs are designated 45, and are pivoted at 4G and are movable outwardly under the action of flat spring 47, being guided by pins passing thru slots 48. The retaining devices are antomatically released when the body 1() drops to a point in the casing, so that these meinbers 45 project below the bottom of the casing 25. and the mandrel 16 moves upwardly under the expansive force of spring 18, and the cutters 24 n'ioveoutwardly to the position of Figure 3, the co-operating portions 36, 37 and 39 at the upper walls of the vertical slot 29 facilitating the movement of the cutters to operative position.

' It will be observed that the contact between surfaces 36, 37 and 39 approaches cam action.

Spring 18 is compressed by pulling down on element 20, and the mandrel 1G moves downwardly engaging the upper curved surfaces of dogs 40 and 41, forcing these dogs outwardly andy permitting the ,mandrel to This releases the dogs 40 and 41,-

pass to the position o't' Figure li. In this operation the dog's iirst inove outwardly, being pivoted in the slot-s i3 of the devices 45, and then said dogs and devices l5 inove inwardly, lthe dogs engaging the mandrel, and the cutters being in the position of Figure 2, so that the whole mechanism inay pass without diiiiculty' thru the well casing, until-release is effected automatically at the lower end of the casing, as described, because springs 47 are tree to act and carry the dogs outwardly for releasing the mandrel 16,' so that the latter and the' cutters 24tinay inove to the position of Figure 3.A

Having' thus described the invention, Wha is claimed as new, is:

In a device oi" the class described, a body having a vertical bore and having slots coininunicating with the bore, cutting devices within the slots and adapted to bear against the upper calls thereof, the cutting devices including upper slotted portions, a mandrel within the bore and means on the 1nandrel for engaging the slotted portions last named, means for retaining the cutting devices inactive, and a spring for moving the mandrel and cutting devices Iupwardly and outwardly upon release by the retaining ineens, said retainingl means including pivoted dogs and pivoted spring actuated devices mounting the dogs, these devices having guiding slots, and pins passing' transversely thru the slots and into the body portion.

In testimony *whereof I aiix inysignature.

JAMns M. MILLER. 

